From the earliest times when humans began wearing coverings on their feet, there has been an ever present desire to make such coverings more useful and more comfortable. Accordingly, a plethora of different types of footwear has been developed in order to meet specialized needs of a particular activity in which the wearer intends to participate. Likewise, there have been many developments to enhance the comfort level of both general and specialized footwear.
One area of footwear which has received increasing attention in recent years has been athletic footwear. The increasing popularity of athletic endeavors has seen an increasing number of shoe design intended to meet the needs of the participants. The advancements in athletic shoe constructions have especially occurred where the participants are engaged in rigorous movements, such as running, jumping and the like.
It is well understood that, in typical walking and running gaits, one foot contacts the support surface (such as the ground) in a "stance mode" while the other foot is moving through the air in a "swing mode". During the stance mode, a respective foot travels through three successive basic phases: heel strike, mid-stance and toe-off. At faster running paces, the heel strike phase is usually omitted since the person tends to elevate onto his/her toes.
Typical shoe construction fails to completely address the needs of an athlete's foot and ankle during the various stages of the walking and running gait. Traditional shoe constructions result in a loss of a significant portion of the functional ability of the foot during these activities. Losses have been observed in the ability of the foot to absorb shock, in load musculature and tendon systems and in the propulsion of the body. One reason for these deficiencies is the failure of traditional shoe designs to address individually the heel, toes, tarsals, muscles and tendons of a person's foot.
Moreover, in vigorous athletic activities, the athlete generates kinetic energy from the motion of running, jumping, etc. Traditional shoe designs have served merely to dampen the shock from these activities thereby dissipating that energy. Rather than losing the kinetic energy produced by the athlete, it is useful to store and retrieve that energy thereby enhancing the athletic performance. Traditional shoe construction, however, has failed to address this need.
In the last several years, there have been some attempts to construct athletic shoes that provide some rebound thereby to return energy to the athlete. Various air bladder systems have been employed to provide a "bounce" during use. In addition, there have been numerous advancements and materials used to construct the sole the shoe in an effort to make them more "springy".
In my earlier invention disclosed in U.S. Pat. No. 5,647,145 issued Jul. 15, 1997, I teach an athletic footwear sole construction that enhances the performance of the shoe in several ways. First, the construction described in the '145 Patent individually addresses the heel, toe, tarsal and metatarsal regions of the foot to allow more flexibility so that the various portions of the sole cooperate with respective portions of the foot. In addition, a resilient layer is provided in the sole which cooperates with cavities formed at various locations to help store energy.
While the advancements in shoe constructions described above, including the '145 Patent, have provided a great benefit to the athlete, there remains a continued need for increased performance of athletic footwear. There remains a need for athletic footwear sole constructions that can store increasing amounts of kinetic energy for return to the athlete.